Seventy years ago, 156,000 Allied soldiers began their battle for a beachhead on the coast of Normandy, setting off a sequence of events which, along with the advance of Soviet forces in the east, would result in the defeat of German forces which occupied Europe from France to Greece. June 6, 1944, is one of the most important days in the history of our blood-soaked continent. Today, 17 heads of state will take part in memorial services on one of the beaches where thousands of young men died in the effort to turn the tide of war.

What no one could predict in 1944 was that D-Day would lead to the longest period of peace, stability and prosperity that Europe has known. Nor could they imagine that the devotion to peace that was born in the flames of war would be in danger 70 years later – not because of some new military threat but because of the carelessness of leaders who themselves never knew war.

After D-Day, the most important date on the European calendar is July 23, 1952, when the European Coal and Steel Community was established. One year earlier – just six years after the end of World War II – France, West Germany, Italy, Belgium, Luxembourg and the Netherlands had agreed to join in peace and put an end to endless war. The six former enemies were the nucleus of today’s European Union with its 28 member states. Another monumental year was 1989, when the Soviet Bloc collapsed, leading to the accession of eight former Soviet satellites to the EU in May 2004.

Today, 10 years later, the European Union is in crisis. Many member states are in great economic difficulty; deflation, unemployment and debt (public and private) threaten the eurozone; widening inequality between member states and between social groups is reawakening tensions that were dormant in the years of growth and prosperity, threatening the cohesion of the bloc and of many of its members. Looking for ways to ensure their peoples’ welfare even as debt makes this impossible, the EU’s leaders are trapped: On the one hand, they understand the need to strengthen the Union in order to save it, on the other, greater numbers of voters are being seduced by calls for isolationism. Besides these “domestic” issues, the EU is also losing ground on the geostrategic level. The United States’ military and technological hegemony, the economic rise of China and Russia’s hardball politics all contribute to a feeling that the EU is continually losing influence. Its political forces are fragmenting – as is the vision of a Union that can keep improving the lives of its citizens.

The few surviving veterans who will be in Normandy today can be proud of the part they played in what led to a great political, economic and social triumph. The heads of state who will be with them – will they understand that the battle which began then has not ended?